Abstract
A study was conducted to examine ; first, the cardiac response caused by various breath holding maneuvers, body water immersion and underwater swimming (US) ; second, the reproducibility of cardiac response in us; and third, the blood component variations caused by us. Water temperature used was 30°C. Fourteen healthy adults of both gender participated in this study. The results were as follows:
1. Those with stronger bradycardial response to apneic facial immersion (AFI) were subject to induced cardiac arrhythmias during or after us. And those with cardiac arrhythmias caused by AFI were inclined to produce a similar response even when their whole body was immersed as well as during us. Thus the test usingAFI proved to be valuable.
2. Heart rate of almost all subjects repeatedly showed a convex pattern, and their response to cardiac arrhythmias during and after us corresponded fairly accurately. Therefore it is presumed that cardiac function under the influence of US could be reproduced to some extent.
3. During static maneuvers, mainly bradycardiac arrhythmias were detected, including 2°AV block Wenckebach type in case of head out water immersion. On the other hand, brady, tachy and a combination of both were detected under us. From these findings and considering that the subjects with cardiac arrhythmias showed significant and specific variation of blood electrolyte and lactate, it was believed that various factors, including non-reciprocal increase of autonomic activities, the variations of blood component and so forth, simultaneously and interactively caused the cardiac arrhythmias during US.
